Biological samples generally contain nucleic acid sequences which encode information unique to its biological source. For example, all species of acteria which belong to a certain genus (e.g., Campylobacter or Enterobacter) share certain physical characteristics which are encoded by the same nucleotide sequences present in most or all of the species within the genus. Thus, an assay which is specific for the genus can be based upon these common nucleotide sequences.
Detection of nucleotide sequences in a sample can be carried out using nucleotide probes specific for these target sequences. For example, Nagata et al., FEBS, 183:379-382 (1985), describe the use of UV irradiation to bind heterologous high molecular weight DNA to polystyrene microtiter wells in order to detect specific sequences within the immobilized DNA by way of specific DNA probes.
Zouali and Stollar, J. Immuno. Methods, 90:105-110 (1986), describe a technique for the attachment of high molecular weight nucleic acids to polystyrene microtiter wells using pre-treatment of the support with UV irradiation.
Polsky-Cynkin et al., Clinical Chemistry, 31:1438-1443 (1985), describe the use of immobilized capture probes in clinical assays.
Kremsky et al., Nucleic Acids Research, 15:2891-2909 (1987) and Wolf et al., Nucleic Acids Research, 15:2911-2926 (1987) describe a technique for the covalent attachment of oligonucleotides to latex coated polystyrene beads.
Stabinsky, U.S. Pat. No. 4,751,177, describes a single-step target capture that utilizes a hybridization of a tailed capture probe in solution followed by a solid phase capture with oligo-(dT)-controlled pore glass.
Soderlund, UK Patent Application GB 2169403A (1985), describes several affinity-based capture hybridization methods which use two probes, detector probe and a capture probe that contains one member of an affinity pair.
Collins, European Patent Application Number 265 244, describes a nonisotopic reversible target capture protocol which makes use of dA-tailed oligonucleotide probes and oligo(dT)-magnetic particles and poly(dT) filters.
Presently available nonisotopic assay methods are either lacking in sensitivity for certain applications, or are too complex or too slow to be clinically useful. They also require a sample to be split in order to perform multiple assays thereon, resulting in decreased sensitivity. Most of the prior art methods also employ solid phases that are not easily separated from viscous clinical samples, such as stool. It would be helpful to have a rapid, nonisotopic assay useful for assaying complex or unpurified samples that is highly specific, simple to use useful with RNA as well as DNA targets and applicable to clinical and food samples with no prior purification of the nucleic acids of the samples.